Celebrity shoe man Steve Madden pretty much confirmed everyone's suspicion that Ashley and Mary-Kate Olsen aren't the most ideal co-workers, when he candidly called them a "pain in the ass" to work with at last night's star-studded Italian sneaker brand Superga's SoHo party.

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"They are difficult. They are exacting," he told Fashionista.com, after calling their collaboration experience on both the twins' Elizabeth and James shoe line and now the Superga sneakers "painful." "They are a pain in the ass. But they're very good though."

"They're very demanding, they're very tough," he continued. "You know, just tough, tough. They want what they want. And so we worked hard to get that done."

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But give the twins a break -- you don't get a billion dollar fashion empire and fashion icon status at just 25 years old without having some very strict standards...